The present invention relates to hydraulic eddy brakes having at least one stator and one rotor which together form an eddy chamber. Liquid supply conduit means are connected to lead substantially into the center of the eddy chamber. Leakage liquid discharge chambers are located between the bearings of the brake and the eddy chamber proper whereby the rotor shaft of the eddy brake is sealed relative to the stationary housing by noncontacting sealing means. Such brakes are used a dynamometers.
Hydraulic eddy brakes comprise at least one rotor and a stator provided with recesses in their respective facing surfaces. Such recesses are uniformly or symmetrically distributed over the respective circumference or rather annular surface to form one or more eddy chambers. Water eddies are produced in these chambers when the rotor is rotated. The power supplied to the brake is converted into heat due to the hydraulic eddy action. The heat in turn is taken up by the cooling water flowing through the apparatus. When the rotor rotates in the stator a rotating torus shaped body of water is produced in the eddy chamber formed by the rotor and the stator. This body of water causes substantial pressures along the walls of the eddy chamber including along the inner and outer circumferences of the eddy chamber. Due to the pressure along the outer circumference of the eddy chamber the water will flow through a liquid discharge means out of the eddy brake. Incidentally, water is the most commonly used liquid in such brakes. However, any other suitable liquid could also be used, for example oil or the like.
Heretofore it was customary to seal the eddy chamber at its inner circumference by sealing means of elastic materials, for example, so called lip type packings to reduce pressure loss. However, such packings are subject to substantial wear and tear calling for frequent maintenance and overhaul work of the eddy brake usually after relatively short periods of operation such as about two thousand operational hours. Thus, heretofore it was necessary to practically disassemble the entire brake structure before replacing the sealing packings. Accordingly such overhaul work is expensive and time consuming.
German patent publication No. 1,006,180 discloses an eddy brake in which the rotor shaft is sealed without elastic packings. For this purpose the outer walls of the rotor are provided with radial ribs. The rotor forms only a quarter section of the cross section of the eddy chamber. The rotor shaft is sealed relative to the brake housing by means of labyrinth packings or seals. Spaces for discharging leakage liquid are arranged between the labyrinth packings and the bearings of the rotor shaft. So called gland sealing rings are located in said spaces. This type of structure is rather expensive because of the close tolerances to be maintained for the labyrinth packings which are not supposed to contact the rotor shaft. Another drawback of this type of structure is seen in that it is relatively sensitive to rough operating conditions. Besides, due to the stator which is divided in half, the power of such hydraulic eddy brakes is substantially reduced relative to other conventional eddy brakes of the same dimensions.